Abstract: The sarcomere length at static state was investigated in whole sartorius muscle of toad using laser diffraction techniques.The distinct diffraction pattern on a screen which distance from the preparation was 160 cm could be obtained from all the preparations used.The sarcomere length was calculated by Bragg equation,which is related to the distance between the zero and first order lines on the screen. In the present experiments,it was confirmed the sarcomere length near the ends of the muscle was shorter than in the middle and the sarcomere length variation in the middle was extremely small.The sarcomere length of the slack muscle was 2.12±0.04μm(X±SD n=12). The maximum sarcomere length that the mnscle can be stretched was 3.65±0.25μm(X±SD n=12).When the muscle was fixed at the length in the body(functional position),the middle sarcomere length was 2.73±0.02μm(X±SD n=8)in vitro.This result was again confirmed in situ.

Key words: sarcomere length, skeletal muscle, laser, diffraction technique